A. Field of the Invention
The present invention relates to a method of forming, filling and sealing bags continuously and an apparatus for forming, filling and sealing bags. More specifically, the present invention relates to a method of packaging bags continuously in a bag-packaging machine that fills articles to be packaged in a bag while forming the bag by sealing portions of tubular packaging materials, where the tubular packaging materials are conveyed in a downward direction and are sealed after inserting articles therein. The present invention also relates to a bag packaging mechanism that packages bags by sealing portions of a tubular packaging material in longitudinal and latitudinal directions while inserting articles to be packaged therein.
B. Description of the Related Art
There has been a longitudinal bag-packaging machine that fills articles such as foods to be packaged in a bag while forming and sealing the bag.
For instance, a longitudinal pillow packaging machine forms a packaging material which is a sheet-shaped film into tubular shape by using a former and a tube. Longitudinal seal means seals (heat sealing) longitudinal edges of the tubular packaging materials that are placed one on top of another, thereby making bags. The pillow packaging machine fills articles to be packaged into the tubular packaging materials through the tube. Latitudinal sealing mechanism below the tube seals the upper portion of a bag and the bottom portion of a following bag. Then the pillow packaging machine cuts the middle of the latitudinally sealed portion. In such pillow packaging machine, operations of making a bag and filling articles in the bag occur in a continuous manner.
Some of such bag packaging apparatuses perform packing operations. Packing operations are especially important when articles to be packaged are small in apparent specific gravity but large in size. Examples of such articles include potato chips.
U.S. Pat. No. 4,391,081 and Japanese Laid-Open Patent Application Sho 63-191706 disclose such packing operation. In either method, a portion of the tubular packaging material to be sealed is pressed by stripper rods immediately before a pair of seal portions called seal jaws seals the tubular packaging material latitudinally by holding the tubular packaging material therebetween. In this manner, the portion to be sealed is pressed before the seal portions seal the portion, such that articles in that portion will be packed or pushed down (compressed) to a lower portion of the bag. Consequently, the packing operation attempts to prevent improper sealing that occurs due to some articles being sealed with the tubular packaging material at the time of sealing.
Problem to be solved by the Invention
Recently, there has been an increasing demand for bag packaging apparatuses that are capable of high speed processing. Consequently, there has been a need for high speed conveyance of tubular packaging materials and high speed processing by latitudinal seal mechanisms.
Accordingly, pressing operation also needs to be performed at a high speed. However, if packing operations are performed too fast, a bottom end of a bag which has already been sealed may burst or blowout because of an increase in the internal pressure of the bag during the packing operations performed at an upper end of the bag. The stripper rods in the Japanese reference mentioned above are urged by springs against the packaging material and therefore it is not possible to form a gap between the stripper rods in order to prevent such blowouts. Even if a gap were formed between ends of the stripper rods, thin articles such as potato chips may not be properly packed or pushed down, and some of the articles may remain in the sealing portion. This would nullify the purpose of pushing the materials in the bag away from the region of the sealing portion prior to sealing.
In view of the above, there exists a need for an improved latitudinal seal mechanism for a bag packaging apparatus which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
One object of the present invention is to enable latitudinal sealing without sealing articles to be packaged with the tubular packaging material, even when bags are packaged at high speed.
In accordance with one aspect of the present invention, there is a method of forming bags continuously, including inserting articles to be packaged in a tubular packaging material that is conveyed in a downward direction, and sealing the tubular packaging material to form a bag. The method includes the steps of:
inserting articles to be packaged in a partially formed bag;
sealing a lower end of the bag and an upper end of a preceding bag and simultaneously contacting a portion of the tubular packaging material that subsequently forms an upper portion of the bag in order to begin urging the articles downward.
In accordance with another aspect of the present invention, there is a method of forming bags continuously, including inserting articles to be packaged in a tubular packaging material that is conveyed in a downward direction, and sealing the tubular packaging material to form a bag. The method includes the steps of:
inserting articles to be packaged in a partially formed first bag before bottom and upper ends of the first bag are sealed;
sealing a lower end of the first bag and an upper end of a preceding bag and simultaneously contacting a portion of the tubular packaging material that subsequently forms an upper portion of the first bag in order to urge the articles downward, members contacting the portion of the tubular packaging material being spaced apart with a predetermined gap therebetween; and
sealing a lower end of a second bag and the upper end of the first bag and simultaneously contacting a portion of the tubular packaging material that subsequently forms an upper portion of the second bag in order to urge the articles downward, members contacting the portion of the tubular packaging material being spaced apart with a predetermined gap therebetween.
In accordance with yet another aspect of the present invention, there is a method of forming bags continuously, including inserting articles to be packaged in a tubular packaging material that is conveyed in a downward direction, and sealing the tubular packaging material to form a bag. The method includes the steps of:
inserting articles to be packaged in a partially formed first bag before bottom and upper ends of the first bag are sealed;
sealing a lower end of the first bag and an upper end of a preceding bag;
contacting a portion of the tubular packaging material that subsequently forms an upper portion of the first bag in order to urge the articles downward, members contacting the portion of the tubular packaging material being spaced apart with a predetermined gap therebetween;
inserting articles to be packaged in a partially formed second bag before bottom and upper ends of the first bag are sealed;
sealing a lower end of a second bag and the upper end of the first bag; and
contacting a portion of the tubular packaging material that subsequently forms an upper portion of the second bag in order to urge the articles downward, members contacting the portion of the tubular packaging material being spaced apart with a predetermined gap therebetween.
In the above methods, in each of the contacting steps, the members contacting the portion of the tubular packaging material move downward at a rate greater than a rate of downward movement of the tubular packaging material.
Preferably, each of the sealing steps further includes the steps of:
moving sealing members downward in a pre-pressing process on opposite sides of the tubular packaging material at a rate slightly higher than the rate of downward movement of the tubular packaging material with the sealing members spaced apart from each other by a predetermined gap; and
moving the sealing members into firm contact with the tubular packaging material for sealing the tubular packaging material.
In accordance with another aspect of the present invention, a bag packaging apparatus for producing bags filled with articles to be packaged, includes sealing a tubular packaging material in longitudinal and latitudinal directions to form the bags. The bag packaging apparatus includes forming means for forming a sheet-shaped packaging material supplied thereto into tubular shape for receiving the articles to be packaged. The apparatus also includes a packaging material conveyance mechanism for conveying the tubular packaging material in a downward direction, and a longitudinal seal mechanism for joining in a longitudinal direction overlapping portions of the tubular packaging material conveyed thereto to partially form the bags. A latitudinal seal mechanism joins in a latitudinal direction portions of the tubular packaging material conveyed thereto with a predetermined distance between the portions. The latitudinal seal mechanism is disposed below the forming means and the longitudinal sealing means. A settling mechanism is disposed between the forming means and the latitudinal sealing means, and between the longitudinal sealing means and the latitudinal sealing means. The settling mechanism is adapted for contacting a portion of the tubular packaging material that is subsequently sealed by the latitudinal seal mechanism, the portion becoming an upper portion of one bag and a bottom end of another bag. The settling mechanism is adapted to urge the articles to be packaged downward.
Preferably, the latitudinal seal mechanism includes means for pre-pressing the tubular packaging material prior to sealing such that the portion of the tubular packaging material to be sealed is pressed lightly together just before the latitudinal seal mechanism joins the tubular packaging material in the latitudinal direction.
Preferably, the latitudinal sealing mechanism includes two sealing members and the means for pre-pressing includes cam surfaces such that in response to the sealing members being engaged with the cam surfaces the sealing members pre-press the tubular packaging material with a predetermined gap between the sealing members.
Preferably, the settling mechanism includes two pressing rods supported in the bag packaging apparatus. The two pressing rods are adapted for selective vertical movement with respect to the tubular packaging material with a predetermined gap therebetween while contacting the tubular packaging material. The gap between the pressing rods is greater than the gap between the sealing members as the sealing members pre-press the tubular packaging material.
Preferably, the pressing rods are adapted for selective vertical movement with respect to the tubular packaging material by a distance that is greater than a longitudinal distance in which the sealing members pre-press the tubular packaging material.
Preferably, the settling mechanism is adapted to complete vertical movement in contact with the portion of the tubular packaging material before the latitudinal seal mechanism seals the bottom end of one bag and the upper end of a previous bag.
Preferably, the bag packaging apparatus includes a control unit connected to the settling mechanism for controlling the settling mechanism.
Preferably, the bag packaging apparatus also includes a controller connected to the sealing mechanism for controlling the sealing mechanism.
In the above described methods, when a bottom end of the bag and an upper end of a preceding bag are sealed, a portion of the tubular packaging material that becomes the upper end of one bag and the bottom end of the following bag is contacted prior to sealing to settle the articles in the bag toward the bottom of the bag. In conventional configurations, the tubular material is pressed only just prior to sealing. However in the method of the present invention, the portion that to be sealed (or an area around the portion) is contacted at a step prior to sealing and prior to pre-pressing in order to help the articles in the bag to settle to the bottom of the bag.
In this manner, a predetermined portion of the bag is cleared of articles prior to sealing. Further, the settling mechanism contacts the tubular packaging material over a predetermined contact distance to insure packing of the articles away from the portion of the tubular packaging material to be sealed. Therefore, the tubular packaging material can be sealed securely without interference with articles inside the soon to be formed bag, even when bags are packaged at a high speed. Also, since the upper end is pressed when the bottom end is sealed, the bottom end is not likely to blowout during the settling process.
In the settling process, it is preferable to contact a portion of the tubular packaging material that is to be sealed prior to the sealing process. However, if it is difficult to press the portion due to problems such as a conflict between the member to be sealed and the sealing member, the area around the portion to be sealed can be contacted instead. Articles are moved from the portion of the tubular packaging material that is to be sealed.
By the above described method, bags can be filled and sealed continuously at a rapid rate because the articles within the tubular packaging material are packed downward or urged downward by the settling mechanism. As one bag is sealed, the next bag is already filled and being packed by the settling mechanism, soon to be ready for sealing.
The method of the present invention includes pre-pressing by the sealing mechanism and packing by the settling mechanism. The settling process gently presses an upper end of the bag (or an area near the upper end) while the bottom end is sealed. Due to manipulations of the articles by the settling mechanism, the articles to be packaged are pushed into the lower portion of the bag by the time the bag reaches the pre-pressing stage of the sealing members. Therefore, burden on the pre-pressing process can be reduced. Moreover, it is highly unlikely that the articles to be packaged will be sealed with in the sealing portion of the tubular packaging material at the time of sealing.
Since the method has both the pre-pressing process of the sealing members and the settling process of the settling mechanism, contact with the tubular packaging material by the settling mechanism does not require firm contact but rather only requires a gentle push downward. The settling mechanism performs a gentle push because the pressing rods of the settling mechanism are always spaced apart from one another by a predetermined gap. Consequently, there is more flexibility as to how the settling process may be configured. For instance, the gap of the settling process at the time of pressing can be made greater, and contact area distance can be made longer if desired.
When large amounts of articles need to be packaged in a bag, the articles are filled in the bag at several different steps. In such a case, conventional method performs shaking process (oscillating process) after every filling process to increase the density of the articles in the bag. However, the method of the present invention can eliminate the shaking process. Since the density of the articles in the bag can be increased through the settling process, shaking process is no longer necessary.
In the bag packaging apparatus of the present invention, the settling mechanism contacts an upper end of a bag and a bottom end of a subsequent bag (or an area near the ends) when the latitudinal seal mechanism joins (seals) a bottom end of the bag. Therefore, the settling mechanism is disposed between the forming means and the latitudinal seal mechanism, and between the longitudinal seal mechanism and the latitudinal seal mechanism.
In this manner, the bag packaging mechanism includes a settling mechanism that is separate from the latitudinal seal mechanism and presses a portion different from the portion to be sealed by the latitudinal seal mechanism. Therefore, the amount of pressing, in other words the pressing distance can be increased as desired. Consequently, the tubular packaging material can be sealed in latitudinal direction without sealing articles to be packaged together, even when the bag packaging apparatus operates at a high speed. Also, since the bottom end of the bag is sealed as the upper end of the bag and the bottom end of the following bag (or the area near the ends) are pressed, it is less likely that the bottom end of the bag will blowout.
The bag packaging apparatus includes the pre-pressing machine as well as the settling mechanism. Therefore, when the tubular packaging material is joined in the latitudinal direction, the articles to be packaged are securely pushed into the lower portion of the bag whose upper end is the joined portion. In this manner, it is even less likely that the articles to be packaged are joined together in the joined portion when the tubular packaging material is joined, thereby enabling more secure joint.
If the settling mechanism should prolong pressing the upper end of the bag (or the area near the upper end) after the bottom end of the bag is joined, it is likely that the bottom end of the bag will blowout, especially since the joint at the bottom end is not tight right after the completion of joint. In the bag packaging apparatus of the present invention, however, the settling mechanism finishes pressing the upper end of the bag (or the area near the upper end) before the latitudinal seal mechanism completes joining the bottom end of the bag. Therefore, by the time the bottom end of the bag is joined, the bag is no longer subject to an increase in pressure due to pressing by the settling mechanism, whereby the bottom end of the bag is not likely to blowout.
Since the movement of the contacting mechanism does not depend on the movement of the latitudinal seal mechanism, the contact distance can be easily made longer.
These and other objects, features, aspects and advantages of the present invention will become more fully apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings where like reference numerals denote corresponding parts throughout.